The Collaborative International Dictionary of English v.0.48:
S'eance \S['e]`ance"\, n. [F., fr. L. sedens, -entis, p. pr. of sedere to sit. See Sit.] A session, as of some public body; especially, a meeting of spiritualists to receive spirit communications, so called. [1913 Webster]WordNet (r) 3.0 (2006):
seance n 1: a meeting of spiritualists; "the seance was held in the medium's parlor" [syn: seance, sitting, session]